The crystal structure of a ferroelectric lead metaniobate containing 10 mole% barium was refined using the Rietveld method on diffraction patterns obtained using multiple diffraction techniques. Cu Kα X-ray diffraction, synchrotron diffraction, and neutron diffraction were used to provide complementary information on the structure of this substitutionally-alloyed compound. Neutron diffraction was used as a starting point for refinement with the X-ray diffraction methods used for final structural refinements. Barium was found to preferentially substitute on lead sites in the lead metaniobate crystal structure.